Strange Occurrences During Git Assessment

During the git assessment I ran into 2 issues that I was able to fix but have no explanations or ideas on how they occurred.

First issue was after using git checkout pictures from the drawings branch I was unable to use git status or leave the pictures branch and it would always give the message: fatal: Unable to read current working directory: No such file or directory.

I was able to fix this by using cd … to change directory to git-repo-management.

Second issue I found was after using mkdir pictures in the pictures branch, the file would also be listed in the drawings and master branch. This seem to have fixed itself after committing changes to the pictures branch.

I am hoping that I can get explanation for what happened and why these issues occurred.